Habitat utilization, feeding, and growth of wild spotted halibut Verasper variegatus in a shallow brackish lagoon: Matsukawa-ura, northeastern Japan

Abstract

Habitat utilization, feeding, and growth of a rare pleuronectid flatfish, spotted halibut Verasper variegatus, were examined in a brackish lagoon in northeastern Japan: Matsukawa-ura. The distribution and date-length data of spotted halibut collected mainly from beam-trawl samplings during 1983-2008 indicated that age-0 juveniles [n = 25, 6.0-18.0 cm total length (TL)] and older spotted halibut (n = 71, 13.8-43.0 cm TL) inhabited almost the entire northern part of Matsukawa-ura. Comparative distribution surveys of spotted halibut, stone flounder, and marbled flounder during 1985-1989 revealed similar distribution patterns of these flatfishes; the highest densities were found around the central part of Matsukawa-ura, although significantly lower abundance was detected for spotted halibut. Linear growth equations of age-0 juveniles demonstrated that spotted halibut were able to achieve high growth after June, probably because abundant prey (e.g., mysids and gammarids) and suitable physical conditions (warmer water temperature and lower salinity) were present. The main prey items shifted from various crustaceans including mysids, caridean shrimps, and anomurans to brachyura Hemigrapsus spp. (C20 cm TL). Our study shows that spotted halibut use the shallow brackish lagoon as an important nursery for juveniles, and also as a feeding ground for young and adults.

Occurrence, distribution and prey items of juvenile marbled sole Pseudopleuronectes yokohamae around a submarine groundwater seepage on a tidal flat in southwestern Japan

“…To date, there has been only minimal information on the occurrence and distribution of juvenile marbled sole in brackish waters (salinity b 25: Wada et al, 2011). In the present study, however, occurrence of juvenile marbled sole was confirmed in the estuary where salinity was b20.…”

“…Juvenile marbled sole settle at about 10 mm total length (TL) in shallow waters (b10 m in depth) and feeds mainly on crustaceans and polychaetes for a couple of months before leaving for deeper waters at 80-100 mm in TL (Takahashi et al, 1987). High tolerance to low salinity conditions has been observed in a laboratory experiment (Wada et al, 2007(Wada et al, , 2011 and aggregation around an area with submarine groundwater seepage has been reported in nature (Ito and Nakagawa, 2002). Therefore, dependence on organic and inorganic matter of terrestrial origin is expected to be highest during their early life history.…”

Migration, residency and habitat utilisation by wild and cultured Japanese eels (Anguilla japonica) in a shallow brackish lagoon and inflowing rivers using acoustic telemetry

“…The salinity of Matsukawa‐ura lagoon is lower than that of the outer sea but fluctuates with the tidal cycle and the inflow of fresh water from the rivers (Wada et al ., 2011, 2017). The water temperature is lowest in February ( c .…”

“…5°C) and highest in August ( c . 23°C–25°C) and shows greater daily and seasonal fluctuations than those of the outer sea (Wada et al ., 2011, 2014). This brackish lagoon is a nursery ground for many coastal fishes and has an abundance of benthic animals (Nemoto et al ., 2007; Wada et al ., 2011; Urabe et al ., 2013), which can be a good food source for Japanese eels (Kaifu et al ., 2013a).…”

“…23°C–25°C) and shows greater daily and seasonal fluctuations than those of the outer sea (Wada et al ., 2011, 2014). This brackish lagoon is a nursery ground for many coastal fishes and has an abundance of benthic animals (Nemoto et al ., 2007; Wada et al ., 2011; Urabe et al ., 2013), which can be a good food source for Japanese eels (Kaifu et al ., 2013a). Glass eels, elvers and yellow‐phase eels have been observed in the inflowing rivers (Kume et al ., 2019, 2020), and a silver eel was captured in the outer sea, 60 km east from the lagoon (Matsuya et al ., 2015).…”